Each October the Earth passes through dust and debris left behind by Halley’s Comet, and the result is the Orionid meteor shower. It peaks on the nights of 21 and 22 October, and it is visible from Bangladesh.
What you can expect
Up to about 20 shooting stars an hour under good conditions — in a genuinely dark sky, 10 to 20. The meteors appear to radiate from the constellation Orion, near the red giant star Betelgeuse, which is where the shower gets its name.
The particles themselves are ancient fragments of Halley’s Comet, entering the atmosphere at 147,600mph. They vaporise on contact with the air, which is the streak you see.
The timing problem
Experts put the best window from midnight on 21 October until dawn. But there is a complication: the moon is 74 per cent illuminated, and that much moonlight washes out the fainter meteors for a large part of the night.
Fortunately it sets before sunrise. The few hours between moonset and first light give a genuinely dark sky, and that is when the shower can be seen properly. If you are going to set an alarm, set it for the small hours rather than midnight.
How to watch
No equipment is needed — no telescope, no binoculars. What you need is a clear sky and an open space. Get away from bright lights, and give your eyes 20 to 30 minutes to adapt to the dark; most people give up long before their night vision has arrived, which is the single most common reason for seeing nothing.
From a Bangladeshi city this is the hard part. Dhaka, Chattogram and Khulna have enough light pollution to erase most of a meteor shower on their own. If you can reach the edge of a town, a rooftop away from street lights, or open ground outside the city, the difference is not marginal — it is the difference between a handful and nothing at all. October also brings haze, so a clear night matters as much as a dark one.
Why it comes round twice
The Orionids are the second meteor shower of the year produced by Halley’s debris. The first is the Eta Aquariids in May. Earth crosses the comet’s trail twice a year, which is why one comet yields two showers.
Halley itself orbits the Sun once every 76 years and will next be visible from Earth in 2061. Anyone watching tonight is seeing pieces of a comet that most people alive now will never see directly — which is a reasonable thing to think about at four in the morning.
If tonight is cloudy
The shower does not switch off after its peak. Orionid activity runs for several days either side, at lower rates, so a clear sky on the 23rd is worth more than a cloudy one tonight. The same applies if you cannot get away from city lights until the weekend — fewer meteors from a dark site usually beats more meteors from a bright one.
And a practical note for anyone taking a phone out to photograph it: a meteor is a fast, faint streak, and phone night modes average several seconds of frames together, which tends to erase exactly that. A fixed camera on a tripod with a long exposure has a chance; a handheld phone almost certainly does not. Watching is the better use of the hour.
Related: October’s night sky over Bangladesh.
